Granted Patent
Utility
US 4,921,208 · App. 07/404,945
Proportional flow valve
Inventor:
Drew LaMarca
Patented Case
View Patent ↗
Granted: May 1, 1990
Filed: Sep 8, 1989
Inventor
Drew LaMarca
Assignee (at issue)
Automatic Switch Company
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.